TEMPERATURE-DEPENDENCE OF THE DIELECTRIC-RELAXATION OF PARA-METHYL-ACETOPHENONE, DIMETHYLSULFOXIDE AND THEIR MIXTURES IN DILUTE-SOLUTIONS IN BENZENE

The dielectric absorption of p-methylacetophenbne (PMA) and dimethylsu lphoxide (DMSO) and their mixtures in dilute solutions in benzene has been studied at 9.33 GHz at various temperatures between 7 to 60 degre es C. The relaxation time and thermodynamic parameters, viz. free ener gy, enthalpy and entropy of activation have been determined using the dielectric data. The thermodynamic parameters indicate that the phenom enon of cooperative orientation of molecules as exhibited by the pure liquids is also exhibited by their mixtures. The nonlinear behaviour d f relaxation time in binary mixtures of DMSO and PMA reveals the prese nce of solute-solute and solute-solvent types of af associations. The experimental values of relaxation time of tbe dipolar mixtures have be en compared with the theoretical values obtained by employing differen t methods. The variation of dielectric loss factor epsilon '' with tem perature has been interpreted in terms of Debye dispersion regions.